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Thomas J Silva - One of the best experts on this subject based on the ideXlab platform.
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different dynamic and static magnetic anisotropy in thin permalloy films
Applied Physics Letters, 2003Co-Authors: Radek Lopusnik, J P Nibarger, Thomas J Silva, Z CelinskiAbstract:The values of uniaxial anisotropy Hk in thin polycrystalline Permalloy™ films measured by static and dynamic methods differ by as much as a factor of 1.5. The anisotropy obtained with a pulsed inductive microwave magnetometer in 2.5 to 100 nm thick Permalloy films exhibits an additional isotropic component of 120 to 240 A/m not observed in static measurements. The static value of anisotropy was obtained with an inductive magnetic hysteresis loop tracer. The time-resolved precessional response was measured as a function of in-plane applied magnetic Bias Field and the angle between the easy axis and that of the applied Bias Field. We interpret the constant-offset Field as a transient component of the magnetic susceptibility that affects only dynamical response at time scales below 10 ns.
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damping as a function of pulsed Field amplitude and Bias Field in thin film permalloy
Applied Physics Letters, 2003Co-Authors: J P Nibarger, Radek Lopusnik, Thomas J SilvaAbstract:We have measured the step response in thin film Permalloy as a function of both a hard-axis pulsed Field amplitude and an easy-axis longitudinal magnetic Bias Field using a pulsed inductive microwave magnetometer. The Bias Field ranged from 0 to 8000 A/m (0 to 100 Oe) and the pulsed Field varied from 0.32 to 320 A/m (0.004 to 4 Oe). The rotation angle of the equilibrium magnetization direction varied from 0.002° to 40° for this range of Field values. Data were analyzed to extract the Gilbert damping parameter, α. The damping parameter decreased monotonically with an increase in longitudinal Bias Field. However, there is no observed dependence of α on the pulse amplitude, indicating that the damping is independent of the angle of rotation. We conclude that there is no significant nonlinear generation of spin waves that affects the damping in the case of free induction decay for the range of Field pulses employed.
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inductive measurement of ultrafast magnetization dynamics in thin film permalloy
Journal of Applied Physics, 1999Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T RogersAbstract:An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied Field pulse oriented in the plane of the film and transverse to the anisotropy axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc Bias Field parallel to the anisotropy axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc Bias Field. Damping for both impulse and step excitations exhibits a strong dependence on Bias Field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc Bias Field. Transformation of the data to the frequency domain reveals a higher or...
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inductive measurement of ultrafast magnetization dynamics in thin film permalloy
Journal of Applied Physics, 1999Co-Authors: Thomas J Silva, C G Lee, T M Crawford, C T RogersAbstract:An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied Field pulse oriented in the plane of the film and transverse to the anisotropy axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc Bias Field parallel to the anisotropy axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc Bias Field. Damping for both impulse and step excitations exhibits a strong dependence on Bias Field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc Bias Field. Transformation of the data to the frequency domain reveals a higher order precessional mode which is also preferentially excited at low dc Bias Fields. A possible source for both phenomena is precessional mode saturation for large peak rotations. The technique has the potential for 20 ps resolution, although only 120 ps resolution is demonstrated due to the limited bandwidth of the waveguides used.
D H Wang - One of the best experts on this subject based on the ideXlab platform.
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electric Field controlled magnetic responses in metglas and lead zirconate titanate laminated composite
Journal of Alloys and Compounds, 2013Co-Authors: H C Xuan, D H WangAbstract:Abstract Electric-Field-controlled magnetic responses are investigated in Metglas and lead zirconate titanate based laminated composites by using induction method within different frequencies. The largest value of converse magnetoelectric (CME) coefficient is 4.18 G/V at the resonance frequency of 103 kHz under a low magnetic Bias Field of 45 Oe. Furthermore, the CME coefficient and optimum magnetic Bias Field can be tuned in a wide range by applying dc electric Field Biases. The CME characteristics with the frequency of driving electric voltage, magnetic Bias Field, and different dc electric Field Biases are discussed in present paper.
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large exchange Bias Field in the ni mn sn heusler alloys with high content of mn
Applied Physics Letters, 2010Co-Authors: H C Xuan, Cunlin Zhang, Shiyou Chen, D H Wang, Y W DuAbstract:The exchange Bias properties have been investigated in bulk Mn50Ni40−xSn10+x (x=0, 0.5, and 1) Heusler alloys with high content of Mn, in which the largest exchange Bias Field is up to 910 Oe for Mn50Ni40Sn10 alloy. In these alloys, the excess Mn atoms would occupy not only the Sn sites but also the Ni sites, and the moments of Mn on Sn or Ni sites are coupled antiferromagnetically to those on the regular Mn sites, respectively. The origin of this considerably large exchange Bias Field has been discussed.
J M D Coey - One of the best experts on this subject based on the ideXlab platform.
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irmn as exchange Biasing material in systems with perpendicular magnetic anisotropy
Journal of Applied Physics, 2005Co-Authors: Sebastiaan Van Dijken, J Moritz, Magali Besnier, J M D CoeyAbstract:Contact between a Co∕Pt multilayer and an IrMn film leads to perpendicular exchange Bias. The exchange Bias Field does not depend on the degree of (111) film texture and for Co∕Pt multilayers with IrMn at the bottom it can be enhanced by magnetic Field annealing. The perpendicular exchange Bias of the Co∕Pt–IrMn system is limited by a misalignment between the Co spins and the film normal, which is due to a negative magnetic anisotropy contribution from the Co∕IrMn interface (KSCo∕IrMn=−0.09mJ∕m2). The insertion of a 3A thick Pt layer at the Co∕IrMn interface maximizes the perpendicular exchange-Bias Field.
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correlation between perpendicular exchange Bias and magnetic anisotropy in irmn co pt n and pt co n irmn multilayers
Journal of Applied Physics, 2005Co-Authors: Sebastiaan Van Dijken, J Moritz, J M D CoeyAbstract:Perpendicular exchange Bias has been observed for IrMn∕[Co∕Pt]n and [Pt∕Co]n∕IrMn multilayers in the as-deposited state. The exchange Bias Field is largest when the IrMn film is grown on magnetically saturated Co∕Pt multilayers (8.12mT for n=3), whereas it is considerably smaller when domain formation in the IrMn film occurs before Co∕Pt deposition (3.30mT for n=3). After annealing at 220°C in an out-of-plane magnetic Field the perpendicular exchange Bias Field and magnetic anisotropy are considerably larger for the Co∕Pt multilayers with an IrMn film at the bottom. The apparent correlation between Bias and anisotropy is explained by the dependence of the perpendicular exchange Bias Field on the orientation of the Co spins near the Co∕IrMn interface.
H C Xuan - One of the best experts on this subject based on the ideXlab platform.
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electric Field controlled magnetic responses in metglas and lead zirconate titanate laminated composite
Journal of Alloys and Compounds, 2013Co-Authors: H C Xuan, D H WangAbstract:Abstract Electric-Field-controlled magnetic responses are investigated in Metglas and lead zirconate titanate based laminated composites by using induction method within different frequencies. The largest value of converse magnetoelectric (CME) coefficient is 4.18 G/V at the resonance frequency of 103 kHz under a low magnetic Bias Field of 45 Oe. Furthermore, the CME coefficient and optimum magnetic Bias Field can be tuned in a wide range by applying dc electric Field Biases. The CME characteristics with the frequency of driving electric voltage, magnetic Bias Field, and different dc electric Field Biases are discussed in present paper.
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large exchange Bias Field in the ni mn sn heusler alloys with high content of mn
Applied Physics Letters, 2010Co-Authors: H C Xuan, Cunlin Zhang, Shiyou Chen, D H Wang, Y W DuAbstract:The exchange Bias properties have been investigated in bulk Mn50Ni40−xSn10+x (x=0, 0.5, and 1) Heusler alloys with high content of Mn, in which the largest exchange Bias Field is up to 910 Oe for Mn50Ni40Sn10 alloy. In these alloys, the excess Mn atoms would occupy not only the Sn sites but also the Ni sites, and the moments of Mn on Sn or Ni sites are coupled antiferromagnetically to those on the regular Mn sites, respectively. The origin of this considerably large exchange Bias Field has been discussed.
Nobuo Hayashi - One of the best experts on this subject based on the ideXlab platform.
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influence of longitudinal Bias Field on magnetization distribution in magnetoresistive head with shield films
Journal of Applied Physics, 1994Co-Authors: Chiaki Ishikawa, Yutaka Sugita, Kaori Suzuki, Kazuetsu Yoshida, K Shinagawa, Yoshinobu Nakatani, Nobuo HayashiAbstract:The magnetization distribution in the magnetoresistive (MR) film has been calculated by self‐consistently solving the three‐dimensional Field of the MR head. The magnetization distribution was calculated based on the Landau–Lifshitz–Gilbert equation and the head Field was obtained by the Maxwell equation. The longitudinal Bias Field for the domain control was generated by exchange‐coupled antiferromagnetic or permanent magnetic films which were formed outside the sensing region of the MR film. The resistance change of the MR film was calculated from the magnetization distribution with shield films and without shield films. It was found that the resistance change with the antiferromagnetic film without the shields was about two times larger than that with the permanent magnetic film with the remanence Br of 0.7 T. The difference between them was reduced when the shields were formed because the stray Field from the permanent magnetic film which is applied to the MR film was decreased by the shields. Further...
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simulation of magnetization distribution in magnetoresistive film under a longitudinal Bias Field
Journal of Applied Physics, 1993Co-Authors: Chiaki Ishikawa, Yutaka Sugita, Kaori Suzuki, Naoki Koyama, Kazuetsu Yoshida, K Shinagawa, Yoshinobu Nakatani, Nobuo HayashiAbstract:The effects of longitudinal Bias Field, used for domain control on the magnetization distribution in a magnetoresistive (MR) film, have been investigated by computer simulation. The longitudinal Bias Field was generated by an exchange‐coupled antiferromagnetic or permanent magnetic film formed on the MR film outside the sensing region. It was assumed that the magnetization in the part of the MR film on which the Bias‐generating films were formed was fixed along the easy axis. The spatial sensitivity of the MR film along the track width was evaluated by calculating the dependence of the resistance change on the position of a narrow track recording medium. It was found that the resistance change in the MR film with the anti‐ferromagnetic film was roughly twice as large as the change in the film with the permanent magnetic film. The asymmetric sensitivity profile with respect to reflection about the track width mid‐plane was also obtained. The asymmetry in the track sensitivity profile was found to be caused by three factors: asymmetric magnetization distribution about the track width mid‐plane due to the transverse Bias Field, the difference in angular changes in the magnetization direction in the left and right regions facing the recording medium, and anisotropic flux propagation in the MR film.